builtins: exception, iterator and function attribute surface parity - #950

Builtin/type surface parity work, rebased onto main after #936 merged.
53 files, +2523/-659 across 37 commits.

Themes

• Exception surface — SyntaxError location/offset/source-range rendering, indentation-error classification, file-encoding error formatting, sys.excepthook aliases, exception descriptor validation and delete-rejection, AttributeError pickle state, mutation-safe UnicodeError formatting, ExceptionGroup sequence repr.
• Iterator/type identities — bytes, string, memory, array and unpack iterator types exposed; exhausted list-reverse iterators preserved and released.
• __pypy__ / memoryview — bufferable, newmemoryview, multidimensional subviews, multidimensional count rejection, PickleBuffer public type surface.
• Function objects — __name__/__qualname__/__code__/__dict__ deleters raise the setter's TypeError; method.__class__ delete rejected; method.__dir__ forwards the underlying function's instance dict; func_set_code warns DeprecationWarning when the code object changes the callable's kind.
• Misc bindings — int.from_bytes bytes keyword, stat follow_symlinks, coroutine-origin depth keyword, frozen/builtin module APIs, unicodedata UCD type, identity_dict mapping API, float NaN list ordering, eval/AST compile contracts, wrapped builtin method qualification.

Rebase notes

Four commits were dropped as already upstream via #936's squash merge (UnionType rich-comparison and identity/iteration slots, functools reduce/cmp_to_key exports, the check.py startup median).

One commit — builtins: describe unraisable destructor errors — was dropped as a deliberate resolution. It replaced the __del__ failure report with CPython's Exception ignored while calling deallocator ... label and object=None, but main matches pypy/interpreter/executioncontext.py:690 line-for-line:

report_error(space, e, '', w_del)

The commit carried no test, so the PyPy form was kept. Say so if the CPython wording was intended and it will be restored.

Verification

cargo check --all --no-default-features --features dynasm — clean.
Full gates run here in CI.

Commits

• builtins: add function attribute deleters and method dir forwarding
• memoryview: reject multidimensional count
• builtins: expose string and memory iterators
• builtins: align bytes and unpack iterator surfaces
• builtins: expose bytes iterator identities
• pickle: align PickleBuffer public type surface
• posix: bind stat follow_symlinks keyword
• imp: align frozen and builtin module APIs
• sys: bind coroutine origin depth keyword
• builtins: expose array iterator type
• builtins: preserve exhausted list reverse iterators
• builtins: align type and exception descriptors
• builtins: preserve float NaN list ordering semantics
• builtins: align eval and AST compile contracts
• builtins: align exception type descriptors
• builtins: bind int.from_bytes bytes keyword
• builtins: complete identity_dict mapping API
• builtins: port unicodedata UCD type
• builtins: port pypy bufferable
• builtins: port pypy newmemoryview
• builtins: qualify wrapped builtin methods
• builtins: support multidimensional memoryview subviews
• builtins: classify indentation syntax errors
• builtins: expose missing frame line as None
• builtins: format file encoding errors
• builtins: render SyntaxError file source ranges
• builtins: clamp SyntaxError display offsets
• builtins: preserve compiler SyntaxError locations
• builtins: implement sys excepthook aliases
• builtins: validate SyntaxError details
• builtins: make UnicodeError formatting mutation-safe
• builtins: release exhausted list reverse iterators
• builtins: preserve AttributeError pickle state
• builtins: reject deletion of exception descriptors
• builtins: restore exception state through attributes
• builtins: preserve ExceptionGroup sequence repr
• functools: port reduce and cmp_to_key accelerators

— authored by Claude

Summary by CodeRabbit

• New Features

  • Added Python 3.14-compatible behavior for iterators, memory views, exceptions, coroutine tracking, module detection, and file operations.
  • Improved functools.cmp_to_key and reduce, including keyword arguments and callable key wrappers.
  • Added multidimensional memory view and buffer protocol support.
  • Improved script encoding detection and error reporting.
  • Added identity_dict.keys() and .values() support.
  • Improved Unicode database version handling and sys.excepthook.

• Bug Fixes

  • Corrected exception formatting, syntax-error positioning, Unicode handling, attribute behavior, and iterator state preservation.
  • Improved os.stat handling for keyword-only symlink behavior.